With operation of fluid-technical installations, the monitoring of certain properties of the pressure fluid for evaluating the usefulness of the fluid and for controlling and monitoring of assemblies of machines and the like is of great importance. The evaluation serves for the maintenance of the properties in a state useful for operation of the fluid-technical installations
When a fluid property falls below or exceeds certain boundary values, such property can negatively influence the adaptability for use in a fluid-technical installation during operation. The properties can include, among others:
a) contamination of the fluid with solids; PA1 b) greasing or lubricating properties of the fluid; PA1 c) impurities in the fluid in the form of other substances causing corrosion, especially water; PA1 d) content of decomposition or degradation products in the fluid, causing oxidation, which negatively influences the usefulness by aging the fluid; and PA1 e) fluid supply state of the pumps and/or assemblies of machines, in other words the fill level in the fluid container (the fluid level is referenced in the present framework as a useful property).
In case a circumstance or condition arises during operation which endangers the operational capacity of the relevant installation, automatic measures are to occur to avoid or overcome the problem (for instance switching on the cooling machinery). Alternatively, the operation of the installation must be modified or adjusted to avoid damage In any case, it is critical that the operator be informed of the occurrence of any disturbance, that some protocol take places and that an alarm be triggered.
When a test monitoring of the useful properties of fluids is carried out in a more or less automated manner and an analysis of the test volume is undertaken in the laboratory, an incomplete evaluation of the usefulness of the properties can result This is because the analyses and measurements which are carried out are comparable with one another only when the measurements are collected simultaneously at the different measuring sites. In other words, the sites of the test samplings are in definite space and time relationships to one another With two differently timed and cyclical variable test samples, it cannot be guaranteed that they are taken at the same measurement site A same-time measurement showing two different magnitudes at different sites in the system is affirmable if no gradients are present, for example pressure and temperature gradients.
To avoid this problem, a monitoring arrangement is disclosed in JP-A-63285467. The connection of the sensors with the fluid pump allows the same fluid current flows through both of them. On the basis of one test sample at one single measurement site, a continuous evaluation of different measurements relative to one can be guaranteed, and the same fluid current can pass through a plurality of sensors. A virtually error-free monitoring of the properties of the fluid regarding their usefulness is thus possible.